This invention relates to articles for the prevention of undesired exposure of humans, animals and articles to laser beams. More particularly, it relates to protective barriers such as protective clothing, sheaths for instruments, surgical drapes, endotracheal tubes, vaginal dilators and the like, for use in or during laser-effected surgery or therapy which are useful in the protection of such humans, animals and articles from said undesired exposure to said lasers, said barriers being comprised of hydrophilic xerogels or hydrogels and, if desired, additional additives such as salts, colorants, pigments and medications.
Lasers have recently made a significant breakthrough as a preferred, in some, and the only modality, in other surgical and therapeutic areas. These areas of increasing use of lasers in surgery and other treatments include, e.g., otolaryngology, gynecology and ophthalmology.
Amongst the main advantages of lasers, in surgery, are their ability to incise and/or remove precisely controlled areas of tissue while permitting visual assessment of the procedure through use of an operating microscope. This visual assessment is facilitated by reduction of bleeding and absence of other instrumentation, which might block the surgeon's view, in laser surgery when compared to conventional surgical techniques.
Furthermore, if the blood vessels are sufficiently small they are sealed, by the laser, after incision. If some bleeding were to occur, for instance, in the case of larger blood vessels it can be efficiently stopped by coagulation using a defocused beam, the defocusing being accomplished by partial retraction of the focusing tip, i.e., by increasing the working distance of the laser beam.
Additional advantages of using lasers in surgery are the limitation of the area of undesirable tissue destruction and the zone of devitalized tissue, fewer post-operative complications and less post-operative pain and scar formation which might hinder healing. As a consequence hospitalization time is reduced.
Nevertheless, the use of lasers, in medical treatments and surgery, is not without disadvantages and hazards, chief among which are the danger of fire and the destruction of viable tissue on the margins, or periphery, of the operative site.
As a consequence normal drape procedures commonly used in laser surgery and treatment are of limited value and potentially dangerous. For instance, a fire hazard is especially present when wet Cottonoids (cotton gauze pads wet with saline) which are used to protect the surrounding tissues and organs from exposure to extraneous laser beams, whether direct or reflected, dry out and ignite due to the high inflammability of dry cotton or cellulosics. This is an always present danger due to the high levels of energy associated with laser beams. Thus, it is necessary for the surgical team to be constantly aware of that possibility and to keep the gauze moistened at all times.
Yet other problems arise in the use of drapes on compound surfaces, i.e. surfaces that are not smooth but rather have cavities and ridges, whereby the usual drapes do not conform to the surface topography thereby permitting gaps to be formed between the tissue surface and drape. These gaps permit the gathering of gases and/or heat therein which ultimately result in undesirable tissue damage.
Furthermore, stray beams may impinge on personnel and articles within the operating arena with concomitant damage thereto, e.g., burning the skin of said personnel, charring of clothing, melting of plastic articles, ignition of flammable materials, overheating of equipment, and the like. A. H. Andrews, Jr., and Polanyi, T. G., "Hazards and Safety Considerations When Using the CO.sub.2 Laser" in A. G. Andrews, Jr. (ed.): Microscopic and Endoscopic Surgery With the CO.sub.2 Laser, Boston, MA., John Wright-PSG, Inc., pp75-6, 1982.
An additional aspect of the fire hazard is that the laser beam will burn through most plastics or rubbers of which tubes for insertion into body cavities, e.g., endotracheal tubes and vaginal drapes or dilators, are constructed. Thus, the use of plastic or most rubber endotracheal tubes is usually contraindicated when surgery employing lasers is contemplated. Therefore red rubber tubing or steel, which are less sensitive to lasers, are used, e.g., in the construction of endotracheal tubes. However, because endotracheal tubes prepared from such materials lack built-in cuffs, they do not make completely air-tight seals with the organ walls. To get around that problem it has been necessary to place a separable, inflatable cuff over the distal end of the tube which has, therefore, resulted in the addition of a balloon-filling tube, passed through the larynx, to an already crowded lumen. Furthermore, if the beam impacts upon such a cuff it usually creates a hole or holes therein whereby the inflating medium escapes with a resultant deflation of the cuff and undesirable and potentially dangerous mixing of the environments normally separated by the cuff.
A method to prevent such an occurrence by disposing a thermal shield, comprising a plurality of laser-reflecting petals extending from the outer walls of said tubes to the inner walls of the cavity, between the cuff and the portion of the cavity wherein the surgery or treatment is to be performed, is taught in U.S. Pat. No. 4,378,796.
However, as the above shield functions by "reflecting" the laser beam its use would be diadvantageous to the patient in that the reflected beam may then impact upon healthy tissue, rather than on the surgical site, with deleterious effects thereto.
Additional protection against such undesired impact by the "laser beam [may be provided] by wrapping the tube with an aluminum adhesive tape". . . However, [a]lthough the aluminum tape provides protection, it should not be relied on heavily. . . The tape is only a safety factor and is not absolute." Ibid, p. 77.
Another problem, the destruction of viable tissue near the operative site is due to the fact that, during surgery using lasers, it is often impossible to concentrate the laser exactly and exclusively on the surgical site. For instance, the incident beam may have a larger diameter than the surgical site or part of the beam may be dispersed or reflected, although at a lower intensity, to a distance from the surgical site. This results in undesirable destruction of healthy tissue at the periphery of, and/or at a distance from, the surgical site. The damage occurs in the same manner as the surgery is effected, i.e., by ablative removal of the water (about 90%) and organic matter of which the tissue is comprised.
It has now been found that the articles of the instant invention obviate the above problems thereby providing for enhanced protection of humans, animals and articles during laser-effected surgery and treatments whereby healing of the wounds is facilitated.